vc1parse: implement asf to *-frame-layer stream-format

vc1parse: implement asf to *-frame-layer stream-format

This commit add an helper to convert a frame to frame-layer format and
use it to implement these two stream-format conversion:
- asf --> sequence-layer-frame-layer
- asf --> frame-layer

In simple/main profile, we basically have a raw frame, so building a
frame layer isn't too complicated. But in advanced profile, the first
frame-layer should contain sequence-header, entrypoint, and frame and
each keyframe should contain entrypoint, so we have to handle these
carefully.

https://bugzilla.gnome.org/show_bug.cgi?id=738526